Carnitine, once referred to as vitamin B.sub.T, is a substance participating in the metabolism of fatty acids and the DL-form thereof has heretofore been used as a stomachic. Recently, attention has been directed particularly to L-form thereof.
L-Carnitine is a substance indispensable for the transportation of fatty acids to mitochondria and is used as a transfusion component in the therapy of heart disorders, lipemia, etc. It is also useful as an intermediate for the production of other useful substances such as acetyl-L-carnitine.
For a long time, a chemical synthetic method has been known for the production of carnitine. However, this method is disadvantageous, from the viewpoints of energy consumption and environmental pollution, since it involves heating and use of mineral acids, alkalis or toxic substances and since the resulting carnitine is in the DL-form. Further, L-carnitine has heretofore been produced by optically separating DL-carnitine, obtained by the chemical synthetic method, using a diastereomer method.
Recently, various biochemical approaches have been developed for the production of L-carnitine, for example, hydroxylation of 4-N-trimethylaminobutyric acid (J. Biol. Chem., 256, 1247 (1981)), reduction of 3-dehydrocarnitine (Appl. Environm. Microbiol., 39, 329 (1980)), a method using 4-chloro-3-hydroxybutyric acid ester (Japanese patent application (OPI) No. 118093/84 (the term "OPI" as used herein refers to a "published unexamined Japanese patent application")), a method using crotonobetain as a substrate (Japanese patent application (OPI) Nos. 183694/84 and 118093/84), a method in which DL-O-acylcarnitine is hydrolyzed with an esterase (Biotechnol. Bioeng., 26, 911 (1984)), etc.
These methods are disadvantageous from an industrial viewpoint since the starting materials used are expensive, the enzymes used are unstable and supply of expensive coenzymes is required. Although hydrolysis of carnitinamide with a mineral acid or the like has been known, biochemical hydrolysis of carnitinamide has not heretofore been known.
Further, to date, there have been no reports on a carnitinamide hydrolase which can be used in the production of intermediates for the synthesis of DL-carnitine.